HKPRO Forums banner

1 - 17 of 17 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter · #1 ·
WTK: Muzzel velocity on 16\"barrel HK94 vs handgun

What is the muzzel velocity of an HK94 with the 16" barrel vs a handgun, say a SigSauer P226 or USP using the same ammo, say 115gr-fmj (NO + anything ammo please).

I'm wondering if the 16" barrel gives you muzzel velocity benefits or is past the length of such benefit for a standard handgun 9mm cartidge. Would a shorter barrel actually give you the same or better muzzel velocity?
 

·
Premium Member
Joined
·
153 Posts
Re: WTK: Muzzel velocity on 16\"barrel HK94 vs handgun

Well it's been a couple of days since this was posted and no one's took a stab at it. I was hesitant to because I don't honestly have any solid information to give you. However in the 1980's which was the hey day of the long barreled semi auto assault weapons I recall several gun magazines doing articles on them and it was repeatedly stated a few places that one benefit of the longer barrel with a 9mm round was that it brought it close to the same class as a .357 magnum. I've always wondered if they actually chronographed the rounds to see the velocity increase and compared this to rounds from a .357 revolver (no revolver barrel length was mentioned) Or if it just sounded good to them. At any rate if anyone here disagrees or has better information I certainly have no argument to make. In fact any of you with an HK 94 or an UZI carbine and a chrony might be able to develop some interesting conclusions I'd like to see after all these years.
 

·
Registered
Joined
·
10 Posts
Re: WTK: Muzzel velocity on 16\"barrel HK94 vs handgun

Recently we were testing my friends new chrony and shot some subsonic 9mm loads thru 16" AUG and 10" UZI. We had some handloads and some factory ammo, and to our suprise the handloads vere slower in the AUG than in the UZI. Probably the "pressure curve" in my weak handloads was too fast (158gr bullet and fast powder, the guns worked though), causing the longer barrel friction to start slowing down bullet speed. The factory ammo was some fps faster in the longer barrel, as we predicted it would be.

We are planning to shoot some 9mm loads thru chrony with an sbr in the future and compare the velocities with the ones from Glock 17 , if anybody is interested I can post the results.

Trainer

[This message has been edited by trainer (edited 08-18-2000).]
 

·
Registered
Joined
·
4 Posts
Re: WTK: Muzzel velocity on 16\"barrel HK94 vs handgun

some published figures for 9mm nato ball (115 gr):


1130 fps 4.4 in barrel sig p220
1200 fps 4.9 in barrel beretta 92
1250 fps 6.75 in barrel walther mpk
1312 fps 8.85 in barrel mp5
1350 fps 10.2 in barrel steyr mpi69
1370 fps 10.3 in barrel walther mpl
1470 fps 11.2 in barrel czech m25

couldnt find any info past 11.2 in but imho there would but no decrease in velocity (i would bet an increase).
 

·
Premium Member
Joined
·
153 Posts
Re: WTK: Muzzel velocity on 16\"barrel HK94 vs handgun

Trainer, sure I'd be interested to see the results. And dfs those figures look pretty interesting.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #6 ·
Re: WTK: Muzzel velocity on 16\"barrel HK94 vs handgun

So we still are not sure. I'd expect the velocities to increas as barrel length increases, as the figures posted by dfs indicate, but only to a point. The question is, where is that point. Anyone with a HK94 and a 9mm handgun have a chrono to try this on?
 

·
Registered
Joined
·
4 Posts
Re: WTK: Muzzel velocity on 16\"barrel HK94 vs handgun

my guess is that it would be at some ridiculous length. i saw an article once that tested your question but with rifles and rifle cartridges. i don't remember much about the article, but i remember that they concluded that it was a barrel that was way longer than anybody would ever carry (like 7ft. or something). i would suspect that the gains become trivial near the point where the bullet starts losing velocity i.e. add another ft. in barrel length and get 10 more fps. i would bet (and as trainer pointed out) that barrel, bullet, and powder tolerances from gun to gun and manufacturer to manufacturer play a greater role in small changes in velocity than barrel length. this also shows in my previous post where velocity gains are not an exact function of barrel length and no real formula for determining gains.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #8 ·
Re: WTK: Muzzel velocity on 16\"barrel HK94 vs handgun

I'll agree that its a longer length, but I'm not convince dthat it would be some ridiculously long barrel for a 9mm pistol cartridge. For rifles, I can see that a 30" barrel or longer would proabably be the case, but the 9mm handgun cartridge was specified around a handgun with a short barrel. As such, why would there necessarily be enough powder charge to keep pushing the bullet faster in a 20" or 16" barrel when its mostly used in a 3" to 5" barrel? I would think a rapid burn to get up to max velocity in the initial couple of inches would be it... hence the question.

Well if someone someday does this test, please restart this topic and post the results.
 

·
Registered
Joined
·
4 Posts
Re: WTK: Muzzel velocity on 16\"barrel HK94 vs handgun

the velocity will increase because there is still a considerable amount of force on the bullet even if the powder has completed burning in the barrel. ideally the powder charge should burn to maintain an even pressure through out the length of the barrel. once the powder stops burning the pressure does not go to zero, it just drop parabolicly (remember the gas laws)as a function of barrel volume.

example:
say a bullet is fired from a 5 in barrel. the ideal powder burn would increase pressure to the cartridges rated (say 30000psi) pressure and continue burning to maintain that pressure as the bullet moves down the barrel and the volume increases. lets say that we have an ideal powder burn and the 30000 psi pressure is maintained to the 5 in mark and the powder burns out but this time we are shooting it in a 40in barrel. at 10 in (volume at 5in times 2) the pressure would be 1/2 or 15000 psi. at 20 in it would be 7500 psi and at 40 in it would be 3750 psi and so on. your acceleration is decreasing but this is still a tremendous push on the bullet

last the way that powder burns tends to produce more gas at the begining of the burn than at the end so it is difficult to maintain the maximum rated pressure toward the end of the barrel. this is due to a decreasing surface area of the flamefront on the powder. to compensate for this and maintain pressure pistols usally burn a tremendous amount (relatively) and burn most of it, at the reduced surface area, outside the barrel.

i doubt anybody would be able to test this for you unless they have a really long 9mm barrel


[This message has been edited by dfs (edited 08-22-2000).]

[This message has been edited by dfs (edited 08-23-2000).]
 

·
Registered
Joined
·
955 Posts
Re: WTK: Muzzel velocity on 16\"barrel HK94 vs handgun

I realize this may not address the question directly, but hopefully it provides some insight. I read a test where they progressively removed 2 inch sections from the end of a 22lr 18" barrel and chronographed the results. There was little difference between the 12-18" barrels and less than that the velocities steadily declined. They said that as with most calibers, the much bullet's acceleration occurs close to the chamber. On a side note, tighter chambers and "good" rifiling also produce higher velocities.

I think the real question is what is the ideal as well as most practical barrel length?

Chris

[This message has been edited by tlrgsxr (edited 08-28-2000).]
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #12 ·
Re: WTK: Muzzel velocity on 16\"barrel HK94 vs handgun

For me it was the issue of : if I have to have a 16" barrel to be non-nfa, then would I go with a MP5 barrel with a pinned on fake suppressor or a full 16" barrel. With the 16" barrel you get significantly more muzzel velocity - around 18-20% more - so shooting JHP, for example from the thing, would produce a better performance with the 16" barrel rather than a short barrel with a 10" barrel extension (or whatever it is). Its all based on having a 16" barrel. If I later go to the normal MP5 barrel length- which is more handy, then I'll just get it rebarrelled.
 

·
Registered
Joined
·
4 Posts
Re: WTK: Muzzel velocity on 16\"barrel HK94 vs handgun

wouldnt be too hard to attach a larger diameter extension around the 16" barrel (extending from front sight to end of barrel) to get the supressor look and maintain the higher velocity of the 16" barrel. since the barrel is perminantly attached and meets the min length, the fake supressor could be legally removable. many people use the sd shoud to cover the long barrel of the 94 and keep it looking like a nonsporterized smg.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #14 ·
Re: WTK: Muzzel velocity on 16\"barrel HK94 vs handgun

Right.

For me the issue was one of ease of converson to an SBR. If I get a rifle with an MP5 barrel with a pin-welded 'extension' on it now, then to SBR that sucker, I just have to drill and drop the one pin - easy enough to be done locally and doesn't require buying another barrel. With the 16" barrel, the barrel must be removed, new barrel purchased and then installed - more money and requires having the thing sent to someone competent to do HK barrel install/removal - IE not me or any local smith.
 
G

·
Re: WTK: Muzzel velocity on 16\"barrel HK94 vs handgun

Ok, here goes. I have some data that might be of interest to you. While the guns used aren't always Hk, it does apply to the 16"
vs. pistol length issue.

All test done in Jan 2000, ambient temp 80
1000 feet elevation (approx). Chrono about 20 feet from muzzle. Since my chrono is a cheap job, I averaged from 5-10 rounds for
the average velocity, but don't have the individual strings.

By ammo type, all velocities in fps

9mm Remington Golden Saber 147 gr
Glock 19 (4") 1000
Kel-Tec carbine (16") 1150
SP-89 (4") 1035

9mm Cor-Bon 115 gr +P
Glock 19 1350
Kel-Tec 1500

9mm Blazer 115 gr
Glock 19 1170
Kel-Tec 1450

9mm Winchester Ranger SXT 147 gr
Glock 19 930
Kel-Tec 930

9mm Hirtenberger 90 gr ++P++ (subgun only...)
Glock 19 1350
Kel-tec 1500

And, since you asked so nicely, here's some results that I have on file for the Hk USC carbine versus the Glock 21 (5") barrel:

Cor-Bon 230 gr
Glock 21 920
Hk USC carbine 1075

Cor-Bon 185 gr.
Glock 21 1130
Hk USC carbine 1400

Remington Golden Saber 230 gr
Glock 21 840
Hk USC carbine 980

Winchester 230 gr. ball
Hk USC 930

Sorry if it's hard to read. My impression is that the light, high-pressure loads have a higher velocity jump (long vs. short barrels)
than the heavier, standard loads. As you can see, some loads chrono'd exactly the same speed in a pistol and a carbine. Cor-Bon
seems to be the best in terms of velocity from a 16" barrel.

The .45 ACP Hk USC carbine is screaming out for the .45 super load, but I don't have any to chrono.

One thing that needs to be mentioned- the 16" pistol-caliber carbines are QUIET! I can shoot the Kel-Tec carbine without hearing
protection, and it doesn't hurt. I didn't do this on purpose, of course, and only did it twice (I shot it again to see if it really was that
quiet...). If you had to engage targets in a CQB situation, the 16" would not wreck your hearing as much as a pistol.

Hope this helps.

Simon
 
1 - 17 of 17 Posts
Top